Experimental prediction of deformation mechanism after continuous dynamic recrystallization in superplastic P/M7475 |
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Authors: | T Hirata T Mukai N Saito S Tanabe M Kohzu K Higashi |
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Affiliation: | (1) Department of Metallurgy and Materials Science, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho, Sakai, Osaka, 599-8531, Japan;(2) Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka, 536-8553, Japan;(3) National Institute of Advanced Industrial Science and Technology, Moriyama-ku, Nagoya, 463-8687, Japan |
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Abstract: | The deformation mechanism in high-strain-rate superplastic P/M7475 before and after continuous dynamic recrystallization (CDRX) was investigated. The recrystallization process in P/M7475 differed from that in conventional superplastic material, I/M7475. In I/M7475, the fine-grained microstructure was obtained by static recrystallization before deformation. On the other hand, the substructure in P/M7475 evolved into fine grains during deformation by CDRX. The percentage of high-angle and random boundaries was low at an initial stage of deformation. However, it increased with strain in P/M7475. The microstructural change in P/M7475 influenced a deformation mechanism and affected grain boundary sliding (GBS). The ratio of contribution of GBS to total elongation was low at an early stage of deformation in P/M7475. However, it increased with deformation progressed. It is suggested that the deformation behavior in P/M7475 changed from dislocation creep to superplasticity as the dominant deformation mechanism changed to GBS. The activation energy for superplastic flow in P/M7475 was close to that for lattice self-diffusion in pure aluminum. It is therefore concluded that the dominant deformation mechanism after CDRX in P/M7475 is GBS accommodated by dislocation movement controlled by lattice self-diffusion, similar to that in I/M7475. |
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